Relay



INVENTOR a @I U h ATTORNEY Jan. 30, 1934. o, THOMPSON RELAY Filed July 10. 1931 Patented Jan. 30, 1934 PATENT OFFICE RELAY 0101' Thompson, Long Island City, N. Y., assignor to Takamine Corporation, Long Island City, N. Y., a corporation of New York Application July 10, 1931. Serial No. 549,932

6 Claims.

This invention relates to circuit controlling devices, and with particularity to an improved type of slow-acting or time relay.

An object of the invention is to improve the 6 operation and to increase the reliability of operation of so-called slow-acting relays, such as are ordinarily employed for timing the closure or opening of electric circuits or the like.

Another object of the invention is to provide a dash-pot type of relay with means for insuring uniformity of action of the relay.

In certain types of relays, particularly relays of the dash-pot type employing a needle valve for the purpose of controlling the rate of en- 15 trance or exit of the damping fluid, great dimculty has heretofore been encountered in making a relay which will maintain its uniformity of response and action after a considerable period or" use. t has been found that one of the main causes of the lack of uniformity in operation of ordinary relays of the type under consideration, resides in the clogging of the relatively small passage or valve opening through which the damping fluid must enter and exit. This is par- 26 ticularly true of those relays employing air as the damping medium. Thus in one known type of relay which is very widely used, the rate of operation or response of the relay is controlled by a piston working in a cylinder which is provided with an adjustable valve to control the rate of expulsion and admission of the air. Needless to say, when a relay of this type is not completely enclosed, and. hermetically sealed, that the continual drawing in of air into the cylinder through the valve, carries a quantity of dust and foreign matter which eventually lodges in the valve opening. This dust therefore changes the size of the valve opening and eventually may entirely clog the same.

Accordingly one of the principal features of the present invention is to provide means for protecting the valve in a relay of the abovenoted type, from becoming clogged with dust, liquid or other foreign matter.

Another feature of the invention is to provide a simple guard, ring or shield which may be readily applied to existing relay structures, and which as effectually guards the relay valve as if the entire relay were provided with an hermetically sealed housing.

A further feature relates to the novel organization and arrangement of elements which go to make up a simple and completely reliable "time relay.

Other features and. advantages of the invention, not specifically enumerated, will be apparent after a consideration of the following detailed descriptions and the appended claims.

While the invention will be disclosed herein as applied to one known type of relay structure, it will be understood that this is done merely for explanatory purposes, and that the broad concept of the invention is capable of embodiment in many different types of relays, other than that specifically shown and described.

Referring to the drawing, there is shown in the singlefigure thereof, a timing relay comprising a casing 1, which carries the lugs 2 by means of which the relay may be mounted in any suitable place. Within the casing 1, is a solenoid winding (not shown) which is provided with terminal wires 3 for energizing the winding.

Attached to the bottom of casing 1, is a slab 4 of insulating material to which is fastened in any suitable manner, as by bolts 5, a pair of metallic contact strips 6, having hooked portions '7 at the lower ends thereof. The plunger 8 for the solenoid is in the form of a round bar of suitable para-magnetic material. The lower end of plunger 8 has attached thereto a rod 9 which carries a small disc 10. Slidably mounted on the rod 9 is a larger disc which is adapted to make contact with member 7 when in the position shown in the drawing. A spring 12 is provided between the discs 10 and 11 to take up the shock when disc 11 engages contact 7. A stop nut 13 may be provided to limit the downward movement of disc 11 on rod 9. While the drawing shows a single pair of contacts '7 carried by the member 4, it will be understood that as many contacts as desired may be employed to cooperate with disc 11.

The core 8 has attached at its upper end a piston rod 14 and piston 15 which moves within the piston chamber 16. For the purpose of regulating the rate of egress and ingress of air to the chamber 16, and consequently the rate of movement of the core 8, there is provided at the upper end of chamber 16 an adjustable needle ,valve stem 17 which fits within the valve head 18. The stem is adapted to be adjusted by means of the thumb-nut 19 to control the size of the valve opening. While the valve shown in the drawing is in the formof a conical needle 20, seat 21, the invention may be practised with any other form of valve. The valve wall 18 is provided with a port 23 which communicates with the chamber 16 through the opening 24.

Because of the relatively small diameter of the openings 23 and 24 there is considerable danger if the relay is operated in an atmosphere laden with dust or other foreign particles, that the continual suction and exhaust through said openings will draw in suiiicient dust to eventually clog the same. It has been found that this danger is materially minimized and in most cases completely avoided by providing a guard 25 as shown in the drawing. This guard may be in the form of a hollow conical member adapted to fit snugly around member 18. Preferably, although not necessarily, the wall of the guard 25 is of tapered cross section so as to provide a very small area of contact between the edge thereof and the top of the chamber 16. It has been found that if the edge 26 of the guard which rests on the top of the chamber 16 is unground or unfinished that sufficient natural clearance orleakage is provided to enable the proper quantity of air to be drawn in and exhausted for each operation of the core 8.

It is believed that the guard 25 acts not only as akind of filter or screen to prevent the passage of dust particles therethrough, but also the inclined edge acts to divert the rapidly moving dust particles in the direction of the arrows, thus preventing them from reaching the openings 23 and 24.

The guard 25 is preferably of metal, although any other material such as hard rubber, wood, etc., may be employed. It is not necessary that the guard be rigidly fastened to the member 18, although if the mechanism is to be subjected to excessive vibration it may be found desirable to clamp the guard in position.

While the guard is shown applied to an air dash-pot type of relay, it will be understood that it can be applied to other fluid types of dashpots. In any event, the use of a guard ring on the arrangement shown has been found to exceptionally and unexpectedly increase the reliability and uniformity of the type of relay disclosed.

What is claimed is:

1. In combination a piston, a cylinder in which said piston moves, a valve for controlling the rate of movement of said piston, and a member having a tapered circumferential edge acting as a dust guard for said valve.

2. The combination according to claim 1 in which the dust guard is in the form of a tapered cone of rigid non-foraminous material.

3. In combination a piston, a piston cylinder, means for reciprocating said piston, a valve communicating with said cylinder for controlling the rate of movement of said piston, and a member having a tapered circumferential edge acting as a dust guard surrounding said valve.

4. In combination a piston, a cylinder for said piston, a valve fitted into the piston head and having a stem portion projecting therefrom, a small opening in the stem portion communicating with said cylinder, and a dust guard surrounding the said stem portion, said guard being of rigid non-foraminous material having a ta pered circumferential edge.

5. The combination according to claim 4 in which the dust guard has a portion surrounding the valve stem and has its tapered circumfer'-- ential edge resting on the cylinder head.

6. In combination a cylinder, a piston for: said cylinder, a leakage valve for said cylinder and having a stem projecting from the cylinder head, a dust guard for the valve in the form of a truncated cone having a large tapered rim, the small rim thereof fitting closely around the valve stem, the large rim thereof resting on the cylin der head to permit air to flow through said valve and to exclude dust and other foreign OLOF THOMPSON? 

